From eac4c8ab8130af9da2a5d4eb7a949df7a65656d2 Mon Sep 17 00:00:00 2001
From: Wojtek <wojtek@coreum.com>
Date: Thu, 26 Oct 2023 11:59:11 +0200
Subject: [PATCH] Estimate overhead required by authz execution

---
 .../modules/gas_estimation_test.go            | 83 +++++++++++++++++++
 x/deterministicgas/config.go                  |  7 +-
 x/deterministicgas/spec/README.md             |  2 +-
 3 files changed, 85 insertions(+), 7 deletions(-)

diff --git a/integration-tests/modules/gas_estimation_test.go b/integration-tests/modules/gas_estimation_test.go
index 04d08863e..73198c3e7 100644
--- a/integration-tests/modules/gas_estimation_test.go
+++ b/integration-tests/modules/gas_estimation_test.go
@@ -5,10 +5,13 @@ package modules
 import (
 	"fmt"
 	"testing"
+	"time"
 
 	sdkmath "cosmossdk.io/math"
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	authztypes "github.com/cosmos/cosmos-sdk/x/authz"
 	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/samber/lo"
 	"github.com/stretchr/testify/require"
 
 	integrationtests "github.com/CoreumFoundation/coreum/v3/integration-tests"
@@ -114,3 +117,83 @@ func TestBankSendEstimation(t *testing.T) {
 		fmt.Printf("%d\t%d\n", n, txRes.GasUsed)
 	}
 }
+
+// TestAuthzEstimation it estimates gas overhead required by authz message execution.
+// It executes regular message first. Then the same message is executed using authz. By subtracting those values
+// we know what the overhead of authz is.
+// To get correct results, both authz and bank send must be temporarily configured as non-deterministic messages,
+// to get real results.
+func TestAuthzEstimation(t *testing.T) {
+	t.Parallel()
+
+	ctx, chain := integrationtests.NewCoreumTestingContext(t)
+
+	requireT := require.New(t)
+
+	granter := chain.GenAccount()
+	grantee := chain.GenAccount()
+	recipient1 := chain.GenAccount()
+	recipient2 := chain.GenAccount()
+
+	chain.Faucet.FundAccounts(ctx, t,
+		integration.FundedAccount{
+			Address: granter,
+			Amount:  chain.NewCoin(sdk.NewInt(50000000)),
+		},
+		integration.FundedAccount{
+			Address: grantee,
+			Amount:  chain.NewCoin(sdk.NewInt(50000000)),
+		},
+	)
+
+	// grant the authorization
+	grantMsg, err := authztypes.NewMsgGrant(
+		granter,
+		grantee,
+		authztypes.NewGenericAuthorization(sdk.MsgTypeURL(&banktypes.MsgSend{})),
+		lo.ToPtr(time.Now().Add(time.Minute)),
+	)
+	require.NoError(t, err)
+
+	_, err = client.BroadcastTx(
+		ctx,
+		chain.ClientContext.WithFromAddress(granter),
+		chain.TxFactory().WithGas(chain.GasLimitByMsgs(grantMsg)),
+		grantMsg,
+	)
+	requireT.NoError(err)
+
+	// execute regular message
+	amountToSend := sdkmath.NewInt(2_000)
+	txf := chain.TxFactory().WithSimulateAndExecute(true)
+	resRegular, err := client.BroadcastTx(
+		ctx,
+		chain.ClientContext.WithFromAddress(granter),
+		txf,
+		&banktypes.MsgSend{
+			FromAddress: granter.String(),
+			ToAddress:   recipient1.String(),
+			Amount:      sdk.NewCoins(chain.NewCoin(amountToSend)),
+		},
+	)
+	requireT.NoError(err)
+
+	// execute authz message
+	execMsg := authztypes.NewMsgExec(grantee, []sdk.Msg{
+		&banktypes.MsgSend{
+			FromAddress: granter.String(),
+			ToAddress:   recipient2.String(),
+			Amount:      sdk.NewCoins(chain.NewCoin(amountToSend)),
+		},
+	})
+
+	resAuthZ, err := client.BroadcastTx(
+		ctx,
+		chain.ClientContext.WithFromAddress(grantee),
+		txf,
+		&execMsg,
+	)
+	requireT.NoError(err)
+
+	fmt.Printf("Authz gas overhead: %d\n", resAuthZ.GasUsed-resRegular.GasUsed)
+}
diff --git a/x/deterministicgas/config.go b/x/deterministicgas/config.go
index 1ec46fc28..072d757cf 100644
--- a/x/deterministicgas/config.go
+++ b/x/deterministicgas/config.go
@@ -35,7 +35,7 @@ import (
 const (
 	BankSendPerCoinGas            = 50000
 	BankMultiSendPerOperationsGas = 35000
-	AuthzExecOverhead             = 2000
+	AuthzExecOverhead             = 1500
 )
 
 type (
@@ -95,11 +95,6 @@ func DefaultConfig() Config {
 		MsgToMsgURL(&assetnfttypes.MsgRemoveFromClassWhitelist{}): constantGasFunc(3500),
 
 		// authz
-		// FIXME (v47-deterministic): We need a procedure to estimate the overhead of the authz. Proposal:
-		// 1. Estimate normal message
-		// 2. Estimate the same message executed using authz
-		// 3. Subtract one from the other
-		// We should have an integration test doing this.
 		MsgToMsgURL(&authz.MsgExec{}):   cfg.authzMsgExecGasFunc(AuthzExecOverhead),
 		MsgToMsgURL(&authz.MsgGrant{}):  constantGasFunc(28000),
 		MsgToMsgURL(&authz.MsgRevoke{}): constantGasFunc(8000),
diff --git a/x/deterministicgas/spec/README.md b/x/deterministicgas/spec/README.md
index 656dcd616..c0adfac0a 100644
--- a/x/deterministicgas/spec/README.md
+++ b/x/deterministicgas/spec/README.md
@@ -143,7 +143,7 @@ Real examples of special case tests could be found [here](https://github.com/Cor
 
 `DeterministicGasForMsg = authzMsgExecOverhead + Sum(DeterministicGas(ChildMsg))`
 
-`authzMsgExecOverhead` is currently equal to `2000`.
+`authzMsgExecOverhead` is currently equal to `1500`.
 
 ### Nondeterministic messages